In switched optical networks, network nodes are needed, which can flexibly switch high amounts of high speed data signals between a large number of input and output ports. Today, optical interfaces are commercially available for signal rates of up to 100 Gbit/s. The overall traffic capacity large network nodes can handle today is in the range of up to few terabit per second. Such network nodes are based on high-speed electrical signal switching.
Another approach is based on optical packet switching technology. An optical Add/Drop-Multiplexer for packet traffic, referred to as Packet OADM, has been described in the article “Packet OADMs for the Next Generation of Ring Networks” by D. Chiaroni et al, Bell Labs technical Journal 14(4) 2010, pages 265-284, which is incorporated by reference herein. A Packet OADM is designed for ring applications.
Another high capacity switching system, which has a number of I/O subsystems interconnected through a central space switch driven at a higher rate than the line rate is described in EP2337372A1. The central space switch of this system can be an optical WDM ring, which interconnects all I/O subsystems and where different I/O subsystems transmit and receive at different wavelengths.